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GE Energy engineers have shared solutions for solving problems and reducing costs associated with wind power on a large scale at the China Wind Power 2010 conference.

The group, including Charlie Hatch, Adam Weiss, and Matt Klab, presented a study on how to make wind power more profitable.

Wind turbines are becoming more established as an economically viable alternative to fossil-fuelled power generation.

Wind farms consisting of hundreds of units are now adding a significant amount to world generating capacity.

Hatch said: ‘As the size of wind farms continues to increase, business economics dictate careful asset management to minimise downtime and maximise availability and profits.

‘A wind-turbine condition-monitoring system is essential to achieving that goal,’ he added.

GE Energy’s team has been focusing on improvements in several areas to achieve optimal asset management and maximum profits.

One of the key ways to minimise downtime and detect early warning signs for needed maintenance includes monitoring vibration frequencies: gear mesh frequencies and bearing defect frequencies.

Another area to monitor includes the gearbox, which contains five shafts supported by 12 or more bearings, each of which produces a set of five defect frequencies (outer race element pass, inner race element pass, cage or fundamental train, element spin, and twice element spin).

The combination of mesh frequencies, harmonics, and bearing defect frequencies can make frequency analysis a formidable task.

In addition, wind turbines are variable speed and power machines.

Because of this, specific bearing and gearbox fault frequencies change with speed and must be carefully tracked.

Variable power means variable torque and associated changes in gear meshing forces that can affect vibration amplitudes and mesh harmonic frequency content.

GE Energy continues to incorporate this knowledge and technology into its Bently Nevada Adapt.wind condition-based monitoring system.

The system consists of a Bently Nevada 3701/60 monitor installed up-tower in each wind turbine on the farm and a central farm server.

The monitor uses an Ethernet connection to connect to the farm Scada network, which communicates to the farm server.

The farm server is typically located at the farm central office, collects data from each 3701, and stores it in a local historian.

Adapt.wind software on the farm server is then used to view alarms and data collected from the monitors.

The platform automatically adjusts for wind-turbine speed changes and extracts specific fault frequencies.

To help compensate for the variable power and torque effects, the operating power range of the machine is divided into five bands, or modes, each with separate control over alarm levels.

This allows more consistent comparison when trending data over long periods of time.

The GE team showed that it is possible to detect bearing race cracks at a very early stage, providing plenty of time to monitor and schedule maintenance.

Timely warning is a key part of optimising economic performance of a wind farm and one way that engineers are making wind power a viable alternative energy solution.

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